The present invention is directed to a device for folding a rear flap on a box blank as the box blank is moving in a path through the folding machine.
Devices for folding flaps of a box blank with a rotative folding member, which is mounted on an intermittently rotatable shaft with the rotatable folding member having two folding hooks on each side of the shaft, are known. These folding hooks are mounted opposite to one another on the central axis and are laterally shiftable along the shaft. The box blank is moved along a path over the rotatable folding member so that the hook can hit the flap from beneath the flap and fold it over while the box blank is being moved thereover. The speed of rotation for the shaft and the member is varied by means of cams and levers so that the hook, after engaging the flap, will be moving at a slightly higher speed than the box blank. When folding the flap, the hook should hit it in a given area, which it lies generally at about two thirds of the flaps length taken from the creasing line on which the folding will occur. The shaft of the rotatable folding member is positioned at a given distance from the plane on which the blanks are moving. The length of the hook, for example, the radius of a circle on which the end of the hook moves and the distance between the intermittent shaft and the extremeties of the folding hook has to be adapted either by changing the length of the mounting arm for the hook or by mounting the hook member on the central axis with thickness blocks to make sure that the hook acts in the wanted area of the flap for the given length of time.
U.S. Pat. No. 3,330,185, whose disclosure is incorporated by reference thereto, discloses a device such as discussed hereinabove. The main drawbacks of this device is that there are difficulties in positioning the folding hooks in the wanted areas and the device has a relatively long set-up time required to mount the hooks on the intermittently rotatable axle or shaft.